The present invention relates to a gas circuit breaker and, more particularly to a gas circuit breaker comprising a supporting structure of a fixed electrode suitable for improving the breaking performance and the insulating performance.
As disclosed, for example, in Japanese Patent Application Laid-Open No.4-87126, in a conventional gas circuit breaker, a fixed electrode is supported in a grounded tank through a cylindrical insulator supporting member arranged on a central axis of the grounded tank. Further, a shielding member surrounds around a fixed arcing contact so that an insulation gas heated up to high temperature by an arc generated between contacts is not directly in contact with the insulator supporting member.
Further, as disclosed in Japanese Patent Application Laid-Open No.8-115642, there is known a gas circuit breaker in which a fixed electrode is supported by arranging an insulator supporting member in the outer peripheral side of a fixed electrode and in a lower portion of a grounded tank.
However, when the shielding member surrounds around the fixed arcing contact as in the former gas circuit breaker, the exhausting performance of the insulation gas heated up to high temperature is deteriorated because the exhausting performance of the high temperature insulation gas stagnates inside the shield and consequently the breaking performance may be deteriorated by the high temperature insulation gas particularly, in a small-sized large-capacity gas breaker.
In order to solve this problem, it is considered that the exhausting performance of the high temperature insulation gas is improved by removing the shielding member, but the high temperature insulation gas comes in direct contact with the insulator supporting member supporting the fixed electrode and consequently the insulation is deteriorated due to stain along the surface of the insulator supporting member to decrease the insulation performance.
On the other hand, it is considered that the insulator supporting member is arranged in the outer peripheral side of the fixed electrode and in a lower portion of a grounded tank, as in the latter gas circuit breaker. However, in this method, when electric conductive extraneous objects are mixed into the grounded tank, the mixed electric conductive extraneous objects are easily attached the insulator supporting member to decrease the insulating performance due to the electric conductive extraneous objects.
Furthermore, in a gas circuit breaker in which the bushing portion is attached to the grounding tank in inclining with respect to the vertical direction, a torsion stress as well as a bending stress is also produced in the breaking portion. Therefore, in a case where the fixed electrode is supported by the grounding tank, it is necessary to design the supporting structure capable of allowing the bending stress and the torsion stress. In addition, a load produced at an earthquake or at transporting the gas circuit breaker or an electromagnetic force caused at current conducting acts on the supporting member of the electrode, it is necessary to design the supporting structure capable of allowing these forces.
The present invention is to solve the above-mentioned problems. The first typical object of the present invention is to provide a highly reliable gas circuit breaker which is capable of improving the braking performance and the insulating performance. The second typical object of the present invention is to provide a gas circuit breaker which is tolerable of a stress acting on the supporting member of the electrode. The third typical object of the present invention is to provide a highly reliable gas circuit breaker which is capable of allowing a stress acting on the supporting member of the electrode and at the same time capable of improving the braking performance and the insulating performance.
The present invention is essentially characterized by that an insulator supporting member supports a fixed electrode in an upper side of a central axis of a tank, that is, that the insulator supporting member for supporting the fixed electrode is arranged in an upper-half space of the cylindrical tank to support the fixed electrode. In the present invention, by the construction, a space for exhausting insulation gas heated up to high temperature is formed in the lower side of the central axis of the tank and in the fixed electrode side opposite to the movable electrode so that the insulation gas heated up to high temperature is exhausted to the space. Therefore, it is possible to prevent the insulation gas heated up to high temperature from directly contact with the insulator supporting member and at the same time to improve the performance of exhausting the insulation gas heated up to high temperature.
Further, the present invention is essentially characterized by that the insulator supporting member of the fixed electrode is a solid cone, and the insulator supporting member is a circular frustum having a circular sectional shape or an elliptical frustum having an elliptical sectional shape. In the present invention, by the construction, it is possible to be tolerable of a stress acting on the insulator supporting member. Therefore, according to an embodiment of the present invention, it is provided a gas circuit breaker comprising a tank filled with an insulation medium; a movable electrode arranged inside the tank; a fixed electrode which is supported through an insulator supporting member inside the tank and disposed detachably from and oppositely to the movable electrode; and electric conductive parts individually provided in the movable electrode and the fixed electrode, wherein the insulator supporting member supports the fixed electrode in an upper side of a central axis of the tank.
According to another embodiment of the present invention, it is provided a gas circuit breaker comprising a tank filled with an insulation medium; a movable electrode arranged inside the tank; a fixed electrode which is supported through an insulator supporting member inside the tank and disposed detachably from and oppositely to the movable electrode; and electric conductive parts individually provided in the movable electrode and the fixed electrode, wherein the insulator supporting member is a solid cone.
According to a further embodiment of the present invention, it is provided a gas circuit breaker comprising a tank filled with an insulation medium; a movable electrode arranged inside the tank; a fixed electrode which is supported through an insulator supporting member inside the tank and disposed detachably from and oppositely to the movable electrode; and electric conductive parts individually provided in the movable electrode and the fixed electrode, wherein the insulator supporting member is a solid cone and supports the fixed electrode in an upper side of a central axis of the tank.